package com.jinyou.web.interceptor;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CommonInterceptor extends HandlerInterceptorAdapter {
    private final Logger log = LoggerFactory.getLogger(CommonInterceptor.class);

    /**
     * 在业务处理器处理请求之前被调用 如果返回false 从当前的拦截器往回执行所有拦截器的afterCompletion(),再退出拦截器链
     * 如果返回true 执行下一个拦截器,直到所有的拦截器都执行完毕 再执行被拦截的Controller 然后进入拦截器链,
     * 从最后一个拦截器往回执行所有的postHandle() 接着再从最后一个拦截器往回执行所有的afterCompletion()
     */
    @Override
    public boolean preHandle(HttpServletRequest request,
                             HttpServletResponse response, Object handler) throws Exception {
        request.setAttribute("_stim", System.currentTimeMillis());
        return true;
    }

    /**
     * 在业务处理器处理请求执行完成后,生成视图之前执行的动作 可在modelAndView中加入数据，比如当前时间
     */
    @Override
    public void postHandle(HttpServletRequest request,
                           HttpServletResponse response, Object handler,
                           ModelAndView modelAndView) throws Exception {
    }

    /**
     * 在DispatcherServlet完全处理完请求后被调用,可用于清理资源等
     * <p>
     * 当有拦截器抛出异常时,会从当前拦截器往回执行所有的拦截器的afterCompletion()
     */
    @Override
    public void afterCompletion(HttpServletRequest request,
                                HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        if (null != request) {
            System.out.println(request.getRequestURI() + "-->" + (System.currentTimeMillis() - (Long) request.getAttribute("_stim")) + "(毫秒)");
        }
    }
}
